Modeling of gold circular sub-wavelength apertures on a fiber endface for refractive index sensing

A finite-difference time-domain approach was used to investigate the excitation of surface plasmons of the circular sub-wavelength apertures on an optical fiber endface. This phenomenon provided the basis of a sensitive liquid refractive index sensor. The proposed sensor is compact and has the potential to be used in biomedical applications, having a sensitivity of (373 ± 16) nm per refractive index unit (RIU) as found through the variation of a reflection minimum with the wavelength

A Macro-element for Modeling the Non-linear Interaction of Soil-shallow Foundation under Seismic Loading

This paper presents a macro-element for simulating the seismic behavior of the soil- shallow foundation interaction. The overall behavior in the soil and at the interface is replaced by a macro-element located at the base of the superstructure. The element reproduces the irreversible elastoplastic soil behavior (material non-linearity) and the foundation uplift (geometric non-linearity) at the soil- foundation interface. This new macro-element model with three degrees-of-freedom describes the force-displacement behavior of the footing center. The single element is restrained by the system of equivalent springs and dashpots. The footing is considered as a rigid body. It is solved by a suitable Newmark time integration scheme and implemented in Matlab to simulate the nonlinear behavior of soil-shallow foundation interaction under seismic loading. A reduce scaled soil-foundation system has been tested on a shaking table at the University of Transport and Communications, Hanoi, Vietnam. Five series of earthquake motions were used with maximum acceleration increased from 0.5  to 2.5 . The comparison of numerical results obtained from the simulation and experimentations shows the satisfactory agreement of the model. The proposed macro-element can be used to predict the seismic behavior of a wider variety of configurations

EXPLAINING GEOGRAPHIC, SOCIAL, AND ECONOMIC DIFFERENCES AS DRIVERS OF INTERNAL MIGRATIONS IN VIET NAM: EMPIRICAL FINDINGS FROM PUSH AND PULL FORCES ANALYSIS

Viet Nam has deeply experienced internal migration during its development history, typically movements from rural to urban and across regions since the launch of economic reform policy in 1986. This article adopts the cost-minimization approach to calculate the push and pull forces of the internal migrations across geographic distances of provinces and then explains those forces along with socio-economic factors within 63 provinces and cities in Viet Nam based on the census data during the period 2010–2019. The empirical findings from the solution to cost-migration equations between the number of migrants and the inverse distance across 63 provinces reported that the push and pull forces are quite heteroskedastic, mostly due to differences in geographic, social, and economic development. Not surprisingly, the Mekong River Delta (MRD) is still the most repulsive region for migrants, accounting for 30% of the total number migrants of the country and notable 98% of migrants who moved to the Southeastern (SE) region as the most attractive destination. It is obviously proven that the push and pull forces of migrations in a province correlate strongly and significantly with economic factors including relative incomes and poverty rate rather than human factors such as urbanization, population, and labor forces. Finally, discussions about policy implications of equitable investments across regions in Viet Nam are really necessary and could be a potential for creating job opportunities and improving standards of livelihoods.

A Modified Reactive Powder Concrete Made with Fly Ash and River Sand: An Assessment on Engineering Properties and Microstructure

Containing a high quantity of both fine powders and steel fiber makes reactive powder concrete (RPC) a unique kind of ultra-high strength concrete. However, the cost of manufacture, shrinkage, and hydration heat are increased when silica fume and cement are used in significant amounts. To mitigate these negative consequences and the environmental impact, this study assessed the use of fly ash (FA) with high volume combined with natural-fine river sand (NFRS) in the manufacturing of RPC. FA was utilized to partially substitute cement at 0, 20, 40, and 60 wt% in RPC mixtures that had a set water/binder ratio of 0.2. Thermal conductivity, porosity, water absorption, and compressive strength tests were performed. Furthermore, RPC's microstructure was examined using a scanning electron microscope (SEM). This study also included a cost and global warming potential analysis of RPC production. Test results indicated that a modified RPC with a 60 MPa compressive strength value could be created by using NFRS and a large amount of FA. In comparison to the reference mixture, a higher compressive strength, reduced water absorption, and lesser porosity were observed in RPC when the FA replacement amount was less than 40%. Many FA particles did not engage in the hydration reaction when the FA replacement level was more than 40%, which had a detrimental impact on the RPC's characteristics. In general, using FA to produce RPC has certain benefits for the economy and the environment. It is recommended that 40% of FA be used in actual practice

Impact of Corporate Entrepreneurship and Organizational Culture on Business Performance: The Role of Supply Chain Management

With the expanding multifaceted nature and vulnerability of worldwide inventory chains, interruption occasions are as often as possible happening in production network. Commercial condition is separated into two sorts including inner and outer business conditions. In the examination, our inward business condition is organization culture and inside business condition is supply chain performance (SCP). Therefore, the purpose of this study is to quantify the impact of organizational culture (OC), corporate entrepreneurship (CE) and its components on business performance (BP) through SCP in the non-financial sector of Thailand. Research sample comprises of 120 non-financial firms operating in Thailand. The study finds that SCP fully mediates the relationship between work reinforcement BP and time availability and BP. Whereas, SCP is found to have partial mediation in the relationship between CE BP, OC BP, management support BP, organization boundaries BP and reward reinforcement and BP. Findings of study are important for mangers in understanding and implementation of better OC which leads to CE and will ultimately enhance BP

Magnetic Resonance Imaging Features of Common Posterior Fossa Brain Tumors in Children: A Preliminary Vietnamese Study

BACKGROUND: Magnetic Resonance Imaging (MRI) nowadays plays an important role in the evaluation of posterior fossa brain tumours in children for appropriate diagnosis, treatment planning, and follow-up. AIM: To assess the MRI features of common posterior fossa brain tumours including medulloblastomas, ependymomas, and pilocytic astrocytomas along with the postoperative parameters to contribute the local knowledge to the neuroradiology and neurosurgery fields. METHODS: The study was performed at Children's Hospital 02 from January 2016 to June 2019. In this study, all pediatric patients adopted MRI to evaluate the posterior fossa brain tumours’ characteristics and then underwent surgery to eradicate the posterior fossa tumours. We retrospectively compared the baseline parameters, MRI parameters, and postoperative parameters among medulloblastomas, ependymomas, and pilocytic astrocytomas. RESULTS: There were 62 patients (27 medulloblastomas, 20 ependymomas, and 15 pilocytic astrocytomas) in this research. The main structure of medulloblastomas and ependymomas was predominantly solid, whereas the main structure of pilocytic astrocytomas was superiorly cystic (p < 0.05). Ependymoma tended to extend tumour through foramina of Luschka and Magendie (p < 0.05). Medulloblastomas chiefly showed iso intensity on T2W and FLAIR images meanwhile ependymomas and pilocytic astrocytomas predominantly appeared hyperintensity on T2W and FLAIR images. Medulloblastomas and ependymomas were mostly high intensity on DWI, and low intensity on ADC whereas pilocytic astrocytomas were usually low intensity on DWI and high intensity on ADC. After injecting CE, pilocytic astrocytomas showed a mixed intensity whereas the signal intensity of medulloblastoma and ependymoma on T1CE was generally strong. There were positive correlations between FH diameter and estimated blood loss (r = 0.289, p < 0.05); and surgical time (r = 0.312, p < 0.05). CONCLUSION: MRI plays a crucial role in demonstrating the features of posterior fossa brain tumours for appropriate diagnosis of medulloblastomas, ependymomas, and pilocytic astrocytomas. Medulloblastomas are problematic tumours and the clinicians should also take into consideration in cases of larger feet-to-head diameter of tumours to ensure the efficacy and safety surgery for patients

ESTIMATING THE ECONOMIC VALUE OF THE ECOTOURISM DESTINATION: THE CASE OF TRA SU MELALEUCA FOREST NATURAL PARK IN VIET NAM

In this article, the application of the Individual Travel Cost Method (ITCM) aims at providing a deeper insight into visitors’ preferences and their expenses on marketed and non-marketed services when travelling to the Tra Su Melaleuca Forest Natural Park, an ecotourism destination in An Giang Province of Viet Nam. The empirical findings from the survey of 237 visitors in 2022 showed that the frequency of trips to this recreational site was 1.3 per year on average and relied strongly on the travel costs. Additionally, the estimate of tourism revenues for 2022 of this site was 82,3 billion Viet Nam Dong (VND; equivalent to 3,5 million USD). Meanwhile, its economic value calculated by the ITCM application reaches 206,2 billion VND (or 8,8 million USD). It is obvious that a greater economic value over the monetary amount of revenue also raises several ideas of managerial implications dedicated to the recreational site. It includes building a marketing team for developing recreational services and digital marketing performance, expanding tour services like transportation, lodging, local guides. Finally, enabling local people to engage in dialogues, decision-making, and interest shares is also necessary for the sustainable development of ecotourism

Trends in socioeconomic inequalities in full vaccination coverage among vietnamese children aged 12–23 months, 2000–2014: Evidence for mitigating disparities in vaccination

There has been no report on the situation of socioeconomic inequalities in the full vaccination coverage among Vietnamese children. This study aims to assess the trends and changes in the socioeconomic inequalities in the full vaccination coverage among Vietnamese children aged 12–23 months from 2000 to 2014. Data were drawn from Multiple Indicator Cluster Surveys (2000, 2006, 2011, and 2014). Concentration index (CCI) and concentration curve (CC) were applied to quantify the degree of the socioeconomic inequalities in full immunization coverage. The prevalence of children fully receiving recommended vaccines was significantly improved during 2000–2014, yet, was still not being covered. The total CCI of full vaccination coverage gradually decreased from 2000 to 2014 (CCI: from 0.241 to 0.009). The CC increasingly became close to the equality line through the survey period, indicating the increasingly narrow gap in child full immunization amongst the poor and the rich. Vietnam witnessed a sharp decrease in socioeconomic inequality in the full vaccination coverage for over a decade. The next policies towards children from vulnerable populations (ethnic minority groups, living in rural areas, and having a mother with low education) belonging to lower socioeconomic groups may mitigate socioeconomic inequalities in full vaccination coverage. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Huy Nguyen” is provided in this record*